\begin{tikzpicture}[>=Stealth]
    \draw (0, 0) rectangle (2, 2);
    \draw (2, 0) rectangle (4, 2);
    \draw (4, 0) rectangle (6, 2);

    \draw (0, 0) -- (6,2);
    \draw (1.2, 0.2) node {$\beta$} (0.8, 0) arc (0:18:0.8) (0.9, 0) arc (0:18:0.9);

    \draw (2, 0) -- (6,2);
    \draw (3.0, 0.2) node {$\alpha$} (2.8, 0) arc (0:27:0.8);
\end{tikzpicture}
